The present invention relates to a floor conveyor system for transporting goods which are preferably arranged on carrying frames.
Floor conveyor systems typically comprise, among other structures, drag chain conveyors and carrying conveyors, which themselves can be sledge or skid conveyors and carrying chain conveyors. With drag chain conveyors, the material to be transported is conveyed exclusively by dragging or pushing. The conveying means functions so as to pull the goods only and thus does not exercise any load-carrying function. Furthermore, the conveying means is usually arranged within or underneath the conveying plane, sometimes even immediately above the conveying plane. By means of wheels mounted on the floorside of the lodging attachments for the goods to be transported, the transport will then take place on a track. While drag chain conveyors require little maintenance to some extent they show considerable disadvantages regarding speed adjusment, accumulation and direction changing capabilities in narrow confines.
With a sledge or skid conveyor, the conveying means not only handles the transport of the goods but also simultaneously exercises load-carrying functions. Thus, the conveyance can be effected via chains or pulleys. Over skids or slide shoes, respectively, the goods to be transported are sitting on the pulleys or chains and are carried along by frictional contact. Sledge or skid conveyors have the advantage that the transporting speed can be quickly adapted to local factors. For example, when operating in assembling shops of the motor car industry, the transport speed can be adapted to accommodate the periodic times required the different processing stations. A drag chain conveyor that can be defined as a continuous conveyor for piece goods, does not offer such a possibility. However, a disadvantage of sledge or skid conveyors is that they typically require rather intensive maintenance caused especially by the plurality of driving means, and that they are prone to being disabled due to the more complicated control mechanism.
It is the object of the present invention therefore to provide a floor conveying system for transporting goods which are preferably arranged on carrying frames, which system brings about a variable transport speed of the goods to be transported, an accumulation of the goods on the most narrow space and which permits quick and reliable change of direction, while at the same time ensuring little and easy maintenance.
According to the present invention, this object is achieved in that the floor conveying system is a combination of a drag chain conveyor and sledge or skid conveyor. A conveying system constructed in such a manner includes all of the advantages that the drag chain conveyor and the sledge or skid conveyor without their respective disadvantages. If, for example, the floor conveyor system according to the present invention is used in assembling shops of the motor car industry, then the drag chain conveyor of favorable maintenance can be put into operation in those areas where there is a very dirty atmosphere as in the paint shop, or where transport takes place over long distances of a substantially straight direction. However, if a change of direction of the goods to be transported is desired to be made on a narrow space or it is desired to distribute the goods into different conveying lines, then the sledge or skid conveyor will be preferred.
Thus, by the teaching according to the present invention, for the first time a conveying system has been provided where that conveyor (e.g. drag chain conveyor or sledge/skid conveyor) can be put into operation which promotes the best solution possible to transport problems. Thus, automobile bodies can be transported through a paint shop, for example, by means of a drag chain conveyor in order to deliver them at the exit thereof to a sledge conveyor which then distributes them to available drying ovens in which the transport is again made by means of drag chain conveyors. The reader should appreciate therefore that in this manner there will be a tremendous saving of space in areas between the paint shop and the drying ovens. In the same manner, a sledge or skid conveyor facilitates the sorting of the delivered material, which first could have been transported by a drag chain conveyor. Thus, the transfer from one conveyor to the other is done by means of conventional transferring equipment.
Changes of direction, e.g. longitudinal transportation in different directions or a cross transportation with the sledge or skid conveyor, are achieved in an embodiment of the present invention in that the goods to be transported, before changing the direction, are taken up by a lifting table along which the cross transportation takes place, at least to some extent.
Consequently, the lifting table represents a section of the sledge or skid conveyor which executes a lifting motion, this section being long enough to accomodate at least one receiving attachment for the goods to be transported. Due to the lifting movement of the lifting table it is guaranteed that the wheels of the receiving attachment for the goods to be transported, at the change of the transport direction, will not engage the conveying attachments, whether they are pulleys or chains, of the adjacent sections of the sledge conveyor.
According to a further embodiment of the invention, the goods being transported in the floor conveyor system can be accumulated.
An arrangement preferably comprising a carrying frame to receive the goods to be transported, with which independent of the available floor conveyor system, transport can be effected without any reloading of the goods to be transported, is provided with wheels as well as skids that are arranged on the floorside of the carrying frame. The floorside contact surfaces of the wheels are on a level different from that of the skids. Consequently, if the carrying frame accomodating the goods to be transported is dragged along on the floor by means of the drag chain conveyor, the skids will not come into contact with the floor and thus there will be no disturbance of the normal flow of the drag chain conveyance. If thereafter the carrying frame is picked up by the skid conveyor, the skids will then come into mutual reaction with the skid conveyor only since the transport level of the skid conveyor is higher than that of the drag chain conveyor in order to obtain a clearance between the wheels of the carrying frame and the floor.
In the preferred embodiment of the present invention there are provided two skids which are arranged in parallel and are separated by a distance relative to each other. Furthermore, the skids extend parallel to the main transport direction. Moreover the wheels are preferably arranged outside the skids, the length of which can be whatever is desired e.g. smaller than the axle distance of the outermost wheels.
It must further be pointed out that the arrangement should include a carrying frame, on which the goods to be transported can be put and which at its floor-side includes the wheels and skids.
By this accomodation arrangement according to the present invention, for the first time it has now become possible to transport the goods not only on a drag chain conveyor but also on a skid or sledge conveyor with only one carrying frame for the goods to be transported.